[CP2K-user] [CP2K:15362] Problem converging SCF for a system containing Fe2+

[Matt W]

Reduce the ALPHA value in &SCF / &MIXING

https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/SCF/MIXING.html

the default is much to large and causes the oscillations.

OT is often a faster / more reliable solver for non-metals.

Matt

On Friday, May 14, 2021 at 12:37:44 PM UTC+1 salo... at gmail.com wrote:

> Hi Pierre, 
>
> Thank you so much for your answer, 
>
> I have added all your suggestions:
> - I am using DZVP-MOLOPT-SR-GTH for all atoms. 
> - I have added CHARGE 0 and MULTIPLICITY 2 ( I am not completely sure 
> about this but I have 55 atoms.).
> - I have expanded the Cutoff as follows:
>
>  &MGRID
>
>       CUTOFF 400
>
>       REL_CUTOFF 60
>
>       NGRIDS 5
>
>     &END MGRID
> I still have the same problem. I am worried because the Convergence of the 
> SCF optimisation up instead of decreasing. 
>
>  Step     Update method      Time    Convergence         Total energy    
> Change
>
>   
> ------------------------------------------------------------------------------
>
>      1 P_Mix/Diag. 0.40E+00   25.1     1.97116897      -352.7972578538 
> -3.53E+02
>
>      2 P_Mix/Diag. 0.40E+00   22.1     1.15920278      -353.8713026582 
> -1.07E+00
>
>      3 P_Mix/Diag. 0.40E+00   22.5     0.70468277      -354.5020638040 
> -6.31E-01
>
>      4 P_Mix/Diag. 0.40E+00   22.5     1.81519648      -354.7042785765 
> -2.02E-01
>
>      5 P_Mix/Diag. 0.40E+00   22.6     1.40667909      -353.4830224789  
> 1.22E+00
>
>      6 P_Mix/Diag. 0.40E+00   22.6     1.61367789      -352.6169777702  
> 8.66E-01
>
>      7 P_Mix/Diag. 0.40E+00   22.8     9.77791081      -349.7222190083  
> 2.89E+00
>
>      8 P_Mix/Diag. 0.40E+00   22.7     3.04606642      -338.8207963019  
> 1.09E+01
>
>      9 P_Mix/Diag. 0.40E+00   22.9    10.99358257      -288.8580020934  
> 5.00E+01
>
>     10 P_Mix/Diag. 0.40E+00   22.9     5.98455238      -271.1871548265  
> 1.77E+01
>
> ...
> And after this remains between 4 and 5 for a long time. 
>
>
> Thanks, 
>
> Salome
>
> On Friday, 14 May 2021 at 13:03:25 UTC+2 pier... at gmail.com wrote:
>
>> Hi Salome,
>>
>>  
>>
>> Two things come to my mind, first you should specify the charge and 
>> multiplicity of your system. Then, the cutoff and rel_cutoff might be too 
>> small.
>>
>>  
>>
>> Actually, there’s a third: why mixing MOLOPT and MOLOPT-SR? Just go with 
>> the latter, they usually work fine.
>>
>>  
>>
>> Regards,
>>
>> Pierre
>>
>>  
>>
>> *From: *c... at googlegroups.com <c... at googlegroups.com> on behalf of 
>> salo... at gmail.com <salo... at gmail.com>
>> *Date: *Friday, 14 May 2021 at 11:53
>> *To: *cp2k <c... at googlegroups.com>
>> *Subject: *[CP2K:15362] Problem converging SCF for a system containing 
>> Fe2+
>>
>> Dear all, 
>>
>>  
>>
>> I am quite new to CP2K and working with transition metals. 
>>
>>  
>>
>> I am trying to reproduce some results of an O2 molecule dissociating from 
>> an heme group (Fe2+). I am struggling to converge the SCF wavefunction even 
>> in a singlepoint calculation and I am not sure what I am doing wrong here. 
>>
>>  
>>
>> As an initial guess, I am using PBE with the following combination of 
>> basis sets and pseudopotentials: 
>>
>> - Fe: BASIS_SET DZVP-MOLOPT-SR-GTH & GTH-PBE-q16. 
>>
>> - All the other atoms: DZVP-MOLOPT-GTH with GTH-PBE-q* . 
>>
>>  
>>
>> I have attached the input file and the initial geometry.
>>
>>  
>>
>> Can you help me out? 
>>
>>  
>>
>> Thank you very much in advance, 
>>
>>  
>>
>> Salome
>>
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>>
>
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